In November 1995, after three days of deliberations in Madrid’s Palacio de Congresas, the Intergovernmental Panel on Climate Change (IPCC) reached the historic finding that “the balance of evidence suggests a discernible human influence on global climate”. This sentence changed the world. While other individuals and national scientific organizations had reached similar conclusions before Madrid, the “discernible human influence” statement marked the first time that the international climate science community had spoken so clearly and forcefully. The reaction was swift. The “discernible human influence” conclusion led to Congressional investigations, charges of “scientific cleansing”, allegations of corruption of the peer-review process and professional misconduct, and claims of political tampering. Santerspent several years addressing such criticism. This lecture is a reflection on some of the scientific and personal lessons he learned after publication of the IPCC’s 1995 Report. Many of these lessons still have relevance in today’s world.